Table 6.

Exponential relationship between spectral reflectance measurements and sugarcane crop yield component as a function of time in St. Gabriel and Jeanerette, Louisiana from 2008 through 2011, using cumulative growing degree days (CGDD) and day from the beginning of the year (DFY) when growing degree days > 0.

	Coefficient of Determination (r2)
	Cane Tonnage			Sugar Yield
Growth Stage	NDVI	INSEY-DFY †	INSEY-CGDD ‡	NDVI	INSEY- DFY	INSEY-CGDD
CGDD
150–300	NS §	NS	NS	NS	NS	NS
301–450	NS	NS	NS	0.30	NS	0.25
451–600	0.24	NS	0.24	0.22	NS	NS
601–750	0.20	0.23	0.46	0.21	0.33	0.42
>751	NS	0.19	0.31	0.15	0.19	0.22
DFY
116–123	NS	NS	NS	NS	NS	0.10
124–131	NS	NS	NS	NS	NS	NS
132–139	0.07	NS	NS	0.11	NS	NS
140–147	NS	NS	0.21	0.11	0.15	0.34
148–155	NS	0.05	0.21	NS	NS	0.15
156–163	NS	0.25	0.31	NS	0.28	0.34

^†NDVI measurement adjusted for days from beginning of year (DFY) where the growing degree days are >0;

^‡NDVI measurement adjusted for cumulative growing degree days (CGDD);

^§Indicates the relationship was not significant at a 0.05 level.